Assembly of an end-fitting and an unbonded flexible pipe

Abstract

An end-fitting and an unbonded flexible pipe, where the unbonded flexible pipe includes from the inside and out an internal pressure sheath, at least one armor layer and an outer sheath, the end-fitting further includes a sealing element. The sealing element includes a seal casing concentrically arranged around the internal pressure sheath, the seal casing includes a recess in which a first sealing element is concentrically arranged around the internal pressure sheath such that the surface of the first sealing element at least forms a line contact with the internal pressure sheath, and a second sealing element is concentrically arranged around the internal pressure sheath in the recess such that the surface of the second sealing element at least form a line contact with the surface of the seal casing and form a line contact with the surface of the first sealing element.

What is claimed is: 
     
       1. An assembly of an end-fitting and an unbonded flexible pipe,
 said unbonded flexible pipe comprises from the inside and out an internal pressure sheath, at least one armor layer and an outer sheath, 
 said layers of the flexible pipe being terminated in said end-fitting, and said end-fitting further comprises a sealing arrangement, 
 wherein said sealing arrangement comprises a seal casing concentrically arranged around the internal pressure sheath, 
 said seal casing comprises a recess in which at least a first ring shaped sealing element is concentrically arranged around the internal pressure sheath to provide that the surface of the first ring shaped sealing element forms at least a line contact with the internal pressure sheath, 
 and a second ring shaped sealing element is concentrically arranged around the internal pressure sheath in said recess to provide that the surface of the second ring shaped sealing element forms at least a line contact with the surface of the seal casing and forms a line contact with the surface of the first ring shaped sealing element and wherein the hardness of the first ring shaped sealing element is different from the hardness of the second ring shaped sealing element; and 
 the Shore D hardness of the first ring shaped sealing element is in the range of 40 to 70 measured according to ASTM 2240; and 
 the Shore A hardness of the second ring shaped sealing element is in the range of 80 IRHD to 100 IRHD measured according to ISO 48N. 
 
     
     
       2. An assembly according to  claim 1 , wherein the second ring shaped sealing element has a higher elastic strain limit than the first ring shaped sealing element. 
     
     
       3. An assembly according to  claim 1 , wherein the seal casing comprises a third ring shaped sealing element concentrically arranged around the internal pressure sheath in said recess to provide that the surface of the third ring shaped sealing element forms at least a line contact with the surface of the seal casing and forms a line contact with the surface of the first ring shaped sealing element. 
     
     
       4. An assembly according to  claim 3 , wherein third ring shaped sealing element corresponds to the second ring shaped sealing element. 
     
     
       5. An assembly according to  claim 1 , wherein the surface of the first ring shaped sealing element comprises a groove concentrically arranged around the internal pressure sheath. 
     
     
       6. An assembly according to  claim 5 , wherein the groove houses a fourth ring shaped sealing element, said fourth ring shaped sealing element forms at least a line contact with the internal pressure sheath and a contact with the surface of the first ring shaped sealing element. 
     
     
       7. An assembly according to  claim 1 , wherein the Shore D hardness of the first ring shaped sealing element is in the range of 45 to 65 measured according to ASTM 2240. 
     
     
       8. An assembly according to  claim 1 , wherein the Shore A hardness of the second ring shaped sealing element is in the range of 82 IRHD to 98 IRHD measured according to ISO 48N. 
     
     
       9. An assembly according to  claim 1 , wherein the second ring shaped sealing element is made from a cross-linked polymer material. 
     
     
       10. An assembly according to  claim 9 , wherein the first ring shaped sealing element is made from a polymer material, and wherein a degree of crosslinking of the polymer material of the first ring shaped sealing element is at least 10 times lower than the degree of crosslinking of the second ring shaped sealing element. 
     
     
       11. An assembly according to  claim 1 , wherein the first ring shaped sealing element is made from a thermoplastic polymer material. 
     
     
       12. An assembly according to  claim 1 , wherein the first ring shaped sealing element is made from a thermoplastic polymer material reinforced with particles, flakes or fibres. 
     
     
       13. An assembly according to  claim 1 , wherein the first ring shaped sealing element is made from polytetrafluoroethylene (PTFE), thermoplastic elastomer (PTE), perfluoroalkoxy alkane (PFA), poly(fluorenyle ethynylene) (PFE), polyurethane (PU), ultra high molecular weight polyethylene (UHMWPE) or polyetheretherketone (PEEK). 
     
     
       14. An assembly according to  claim 1 , wherein the second ring shaped sealing element is made from one or more elastomers as defined by ASTM D1418. 
     
     
       15. An assembly according to  claim 1 , wherein at least one of the first ring shaped sealing element and the second ring shaped sealing element is made from fluoro-containing polymer material. 
     
     
       16. An assembly according to  claim 1 , wherein the recess in the seal casing has a rectangular cross-section. 
     
     
       17. An assembly according to  claim 1 , wherein the seal casing has a substantially U-shaped cross-section. 
     
     
       18. A method of applying a seal casing in an assembly of an end-fitting and an unbonded flexible pipe, where
 said unbonded flexible pipe comprises from the inside and out an internal pressure sheath, at least one armor layer and an outer sheath, 
 said layers of the flexible pipe being terminated in said end-fitting, wherein the seal casing is arranged concentrically around the internal pressure sheath, 
 said seal casing comprises a recess in which at least a first ring shaped sealing element is concentrically arranged around the internal pressure sheath such that 
 the surface of the first ring shaped sealing element is arranged to form at least a line contact with the internal pressure sheath, 
 and a second ring shaped sealing element is arranged concentrically around the internal pressure sheath in said recess to provide that the surface of the second ring shaped sealing element forms at least a line contact with the surface of the seal casing and form a line contact with the surface of the first ring shaped sealing element and wherein the hardness of the first ring shaped sealing element is different from the hardness of the second ring shaped sealing element; and 
 the Shore D hardness of the first ring shaped sealing element is in the range of 40 to 70 measured according to ASTM 2240; and 
 the Shore A hardness of the second ring shaped sealing element is in the range of 80 IRHD to 100 IRHD measured according to ISO 48N. 
 
     
     
       19. The method according to  claim 18 , wherein the first ring shaped sealing element and/or the second ring shaped sealing element is/are manufactured from fluoro-containing polymer material.